Paint brush



FIG. 1 is a perspective view of the paint brush showing my new design;

FIG. 2 is a left side view thereof, the right side view being a mirror image of the left side view;

FIG. 3 is a front view thereof, the rear view being a mirror image of the front view;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof.

The dashed line showing of structural lines is included for the purpose of illustrating non-claimed subject matter and forms no part of the claimed design 

The ornamental design for a paint brush, as shown and described. 